A method for preparing lithium manganese iron phosphate positive electrode material using ethyl cellulose as carbon source

Abstract

The invention discloses a method for preparing a lithium-iron manganese phosphate positive electrode material by employing ethyl cellulose as a carbon source. The method comprises the following steps of (1) weighing a manganese source compound, an iron source compound and a phosphorus source compound and then dissolving the manganese source compound, the iron source compound, the phosphorus source compound and a reducing agent into a solvent I to obtain a solution A, dissolving a lithium source into a solvent II to obtain a solution B, dropwise adding the solution B to a precursor solution of lithium manganese phosphate and putting the solution in a high-temperature and high-pressure reaction kettle for reaction for 1-20 hours to prepare a lithium-iron manganese phosphate precursor material; (2) carrying out ball-mill mixing on the precursor material obtained in the step (1) and the ethyl cellulose at the mass ratio of (1-30):1 to obtain a mixture; and (3) drying the mixture, then putting the mixture into a tube furnace for sintering and finally obtaining the carbon-coated lithium-iron manganese phosphate positive electrode material. The thickness of a carbon film on the surface of the positive electrode material obtained by the method is small, so that the electrochemical properties of the material are significantly improved.

Description

technical field [0001] The invention relates to the field of preparation of positive electrode materials for lithium ion batteries, in particular to a method for preparing lithium manganese iron phosphate positive electrode materials by using ethyl cellulose as a carbon source. Background technique [0002] Since Sony first launched commercial lithium-ion batteries in 1991, lithium-ion batteries have been widely used in people's work, All aspects of study and life. In recent years, with the increasing market demand for power batteries and large-scale power energy storage devices, power and energy storage power sources using lithium-ion batteries as carriers have emerged one after another. [0003] Most of the cathode materials used in consumer batteries are LiCoO 2 , because of its high price, toxicity and other disadvantages, it is not suitable for power battery applications with higher energy density and safety. The vigorous development of pure electric vehicles and hyb...

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Problems solved by technology

The above method uses sucrose as the carbon source, and the carbon content in the final compound is about 10%. If the amount of carbon source added is too much, although the rate performance of lithium manganese phosphate can be greatly improved, at the same time, too much added amount of carbon source will lead to synthetic products. The gram capacity is reduced, which affects the capacity of the battery

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